1. Field of the Invention
This invention relates generally to the management of a database utilized in the manufacture of high performance semiconductor devices. More specifically, this invention relates to the management of a recipe database that stores the recipes utilized in scan tools utilized in the inspection of semiconductor wafers during the manufacture of the high performance semiconductor devices.
2. Discussion of the Related Art
In order to remain competitive, a semiconductor manufacturer must continually increase the performance of the semiconductor integrated circuits being manufactured and at the same time, reduce the cost of the semiconductor integrated circuits. Part of the increase in performance and the reduction in cost of the semiconductor integrated circuits is accomplished by shrinking the device dimensions and by increasing the number of circuits per unit area on an integrated circuit chip. Another part of reducing the cost of a semiconductor chip is to increase the yield. As is known in the semiconductor manufacturing art, the yield of chips (also known as die) from each wafer is not 100% because of defects occurring during the manufacturing process. The number of good chips obtained from a wafer determines the yield. As can be appreciated, chips that must be discarded because of a defect increases the cost of the remaining usable chips.
Each semiconductor chip requires numerous process steps such as oxidation, etching, metallization and wet chemical cleaning. In order to etch metal lines, for example, a layer of photoresist is formed on the surface of the semiconductor chips and patterned by developing the photoresist and washing away the unwanted portion of the photoresist. Because the metal lines and other metal structures have xe2x80x9ccriticalxe2x80x9d dimensions, that is, dimensions that can affect the performance of the semiconductor chip, the process of forming the photoresist pattern for each layer is examined during the manufacturing process. Some of these process steps involve placing the wafer in which the semiconductor chips are being manufactured into different tools during the manufacturing process. The optimization of each of these process steps requires an understanding of a variety of chemical reactions and physical processes in order to produce high performance, high yield circuits. The ability to view and characterize the surface and interface layers of a semiconductor chip in terms of their morphology, chemical composition and distribution is an invaluable aid to those involved in research and development, process, problem solving, and failure analysis of integrated circuits.
In the course of modern semiconductor manufacturing, semiconductor wafers are routinely inspected using xe2x80x9cscanningxe2x80x9d tools to find and capture defects. A scanning tool determines the location and other information concerning defects that are caught and this information is stored in a data file for later recapture and inspection of any of the defects. These data files are stored in a relational database that has the ability to generate wafer maps with defects shown in their relative positions. The data database typically has the ability to send these wafer map files to various review tools within the manufacturing plant. This is very useful as it allows for re-inspection on various after-scan inspection tools within the manufacturing plant. These inspection tools include Optical Microscopes and Scanning Electron Microscopes (SEMs) that allow for classification of the defects. Images taken on the various after-scan inspection tools can be linked by linkage data to the defect on a wafer map and reviewed at a workstation at the convenience of an engineer or technician.
In order to be able to quickly resolve process or equipment issues in the manufacture of semiconductor products a great deal of time, effort and money is expended on the capture and classification of silicon based defects. Once a defect is caught and properly described, work can begin in earnest to resolve the cause of the defect, to attempt elimination of the cause of the defect, and to determine adverse effects of the defect on device parametrics and performance. In the course of typical semiconductor manufacturing and processing of semiconductor wafers a great deal of effort is increasingly being placed on determining the quality of the wafers from a defect viewpoint.
In order to scan each semiconductor product and each layer of each semiconductor product, the scan tool must have a recipe for each of the layers. The number of layers can range from approximately 30-50 layers and there may be 10-30 products that are current at any one time. Therefore, each scan tool may have as many as 1500 recipes that are needed to properly scan any of the layers that the scan tool may be required to scan. Tool operators are required to input the recipes into the scan tool and to keep the recipes current. In addition, there are different manufactures of scan tools, different models of scan tools and differences between same models of scan tools. This requires that the recipes be individualized for each layer, for each model tool and for each tool. The large number of recipes makes it difficult to monitor which model has which recipe and what version of recipe is installed on the machine. The recipes control parameters such as the sensitivity, inspection areas, thresholds, light levels, and other setup parameters for every device and layer for which inspection data is required. These recipes basically control how the tool looks at the wafer, what level of difference constitutes a defect, and how much of the wafer will be scanned. The data output from the scan tool as a result of these scans is used to statistically control the manufacturing line and a small variation in defectivity level can trigger a line shutdown. As can be appreciated, the integrity and validity of the recipes used to control the scan tools is critical because of the control of the manufacturing line exerted by these recipes.
There does not exist a method of adequately monitoring, controlling, or even a method of viewing the setup parameters of these critical recipes on a global basis. Even more critical, there is no way to tell if a change has been made to the recipe which could either make it more or less sensitive. Because of this, there is no way to verify that the recipe/tool is not at fault when there is a shift in a performance chart. In addition, there is no record of when recipe was updated and who updated the recipe. Therefore, it is virtually impossible for an operator to know the status of the recipe on any one scan tool and, in addition, it is virtually impossible for an operator to know if the recipes on different machines are the same for scanning the same layer on the same product. Because of the difficulty of determining the status or validity of the recipes on the scan tools, it is difficult to determine the quality of the layer being scanned. This in turn makes it difficult to improve the manufacturing process.
Therefore, what is needed is a system to monitor the recipes that are being input into each scan tool and to monitor the status of the recipes that have been input into each scan tool to ensure that all recipes are up-to-date and are measuring the same parameters.
According to the present invention, the foregoing and other objects and advantages are attained by a scan tool recipe management database system for recipes that includes workstations at each scan tool that simultaneously inputs recipes to the scan tool and to a scan tool recipe database.
In accordance with an-aspect of the invention, changes to the recipes are also simultaneously input to the scan tool and to the scan tool recipe database.
In accordance with another aspect of the invention, defect information generated by the scan tool based on the recipe input to the scan tool is input to a defect management system.
In accordance with another aspect of the invention, a recipe manager determines the status and validity of the recipe at a workstation with access to the scan tool recipe database.
In accordance with still another aspect of the invention, the defect information and the recipe information are correlated to provide yield analysis and trending analysis.
In accordance with still another aspect of the invention, the defect information and the recipe information are input to a SAPPHIRE system where the defect information and recipe information is correlated to provide statistical analysis data.
The present invention thus effectively provides a scan tool recipe management database system for recipes that allows rapid verification of recipe integrity, enables comparison of scan tool to scan tool recipe matching, allows fabrication plant to fabrication plant recipe comparison, provides easy recipe management, enables trending analysis from a recipe change, allows the recreation of old recipes and allows a comparison of recipe setups by different operators.
The present invention is better understood upon consideration of the detailed description below, in conjunction with the accompanying drawings. As will become readily apparent to those skilled in the art from the following description, there is shown and described an embodiment of this invention simply by way of illustration of the best mode to carry out the invention. As will be realized, the invention is capable of other embodiments and its several details are capable of modifications in various obvious aspects, all without departing from the scope of the invention. Accordingly, the drawings and detailed description will be regarded as illustrative in nature and not as restrictive.